Ampule for needleless injection

ABSTRACT

A needleless injection device has a housing containing a pilot valve connectable to a compressed gas source. A two stage power amplifying valve includes a main valve operatively connected to the pilot valve. The pilot valve and main valve form a two-stage valve with the pilot valve activatable to open the main valve utilizing gas pressure. Compressed gas in a reservoir flows through the open main valve to drive a plunger into an ampule to inject an injectant through a patient&#39;s skin. Interlocks are provided to resist inadvertent actuation of the device and a indicator indicates whether there is sufficient gas pressure in the device for another injection.

This is a continuation of U.S. patent application Ser. No. 07/714,892,now U.S. Pat. No. 5,312,335, which is a continuation-in-part of U.S.patent application Ser. No. 07/547,898 filed Jul. 2, 1990 and nowabandoned, which is a continuation-in-part of U.S. patent applicationSer. No. 07/434,250 filed Nov. 9, 1989 and now U.S. Pat. No. 5,064,413.

BACKGROUND OF THE INVENTION

The field of the present invention is needleless hypodermic injectiondevices. More particularly, the invention relates to needlelesshypodermic devices utilizing pressurized gas for injection ofmedication.

Various needleless hypodermic injection devices have been known in thepast. For example, Morrow et al, U.S. Pat. No. 4,790,824 describes aneedleless hypodermic injection device having a two-stage gas deliverysystem and an ampule shroud containing medication which is driventhrough the skin via gas pressure.

Parsons et al, U.S. Pat. No. 4,680,027 discloses an injection deviceusing a pressurized gas cartridge to drive a piston against the biasingforce of a spring. The driven piston works on a syringe causing liquidmedication to be ejected with sufficient pressure to penetrate the skinof the patient.

While these and other known injection devices have met with varyingdegrees of success, their constructions or operating features canprevent effective injection. It has now been discovered that theinjection of liquid medication or injectant should be as instantaneousas possible. With gas powered injection devices, the rise time of thegas pressure acting on the piston, and the resulting acceleration atwhich the piston and injectant are driven is critical. When the gaspressure acting on the piston rises too slowly, the initial medicationejected from the device does not have sufficient pressure or velocity topass through the skin. In addition, if the "rise time" of the injectionsequence is not sufficiently fast, a substantial portion of themedication will be too slowly driven from the device causing a "splashback" condition. Consequently, as a result of "splash back" the patientdoes not receive the full dosage of medication.

In gas driven injection devices, there are several factors which mayeffect the efficiency of the device. For example, devices having a longor tortuous gas path will have slower rise times due to flow losses andgas volume compressibility effects. In addition, certain injectiondevices rely on direct mechanical valve operation by the user of thedevice to release the gas pressure during the injection sequence. Sincethe valve operation is done manually in these devices, the effectivenessof the injection can vary widely with the user, due to the speed,activating force and completeness of activating movement employed bydifferent users of the device. More importantly, it has not beenpreviously appreciated that many of these types of devices haverelatively large "dead" spaces or volumes of gas trapped behind thepiston when the device in the ready to fire condition. These deadvolumes substantially hinder injection by slowing the rise time of thegas pressure acting on the piston since substantial time is required forrelatively large volumes of gas to flow into the dead volumes to buildup an adequate injection pressure.

Gas driven injection devices can also be inadvertently activated if thevalve of the device is inadvertently depressed or opened by the user, orif the user should drop the device, etc. This results in wasted injectedmedication and driving compressed gas.

Gas driven injection devices using compressed gas cartridges can providea limited number of injections before the cartridge must be replacedwith a fresh cartridge. With each injection, some compressed gas isexpended thereby decreasing the available supply of compressed gasremaining in the device. After a certain number of injections, theavailable compressed gas pressure within the device becomes inadequatefor proper injection. Consequently, depending on the type of device andthe type of injections being provided by the device, it has beennecessary for the user of the device to keep track of the number ofinjections provided by the cartridge in the device, and to replace thecartridge after a maximum specified number of injections. If the maximumnumber of injections per cartridge is exceeded, the decreased andinsufficient gas pressure available can lead to "splash back" asdescribed above.

Accordingly, it is an object of the invention to provide an improvedneedleless hypodermic injection device.

It is another object of the invention to provide a novel ampule assemblywhich may be advantageously used with such a needleless injectiondevice.

It is another object of the invention to provide a novel method ofsubcutaneous or intramuscular injection.

It is yet another object of the invention to provide such a needlelessinjection device having an interlock to help prevent inadvertentactuation of the device.

It is still another object of the invention to provide such an injectiondevice having a gas pressure indicator to indicate whether the devicehas sufficient gas pressure for the next injection.

SUMMARY OF THE INVENTION

These and other related objects are achieved according to the inventionby an injection device having a cartridge piercing body within a housingand a valve body in the housing spaced apart from the piercing body. Agas delivery tube extends from the piercing body to the valve body. Areservoir is formed by the valve body and the housing, and the gasdelivery tube has a bleed hole opening into the reservoir. A pilot valveis substantially disposed in a pilot valve chamber in the valve body anda main valve piston is slidably positioned within the housing. The mainvalve piston sealingly engages against a liner seat on a liner. The mainvalve piston faces an annular chamber on one side with the annularchamber connected to the reservoir via a gas passageway. A main valvepiston chamber on the other side of the main valve piston is connectedto the pilot valve chamber. The pilot valve is actuatable to vent thepilot valve chamber. This causes the main valve piston to separate fromthe liner seat such that compressed gas from the reservoir flows pastthe main valve piston into a plunger chamber to rapidly drive a plungerinto a medication ampule for needleless injection through the skin.

These and other related objects are also achieved according to theinvention by an injection device having a trigger actuatable by the userof the device to open the pilot valve. A slide is axially displaceableon the device between a first slide position wherein the slideinterferes with and prevents actuation of the trigger, and a secondslide position wherein the slide is removed from the trigger to allowactuation thereof.

A spring is provided to bias the slide towards the first slide position.A detent collar is provided within a retainer in the slide. The collaris rotatable within the retainer between a first or locked position anda second or unlocked position. A first locking system including a linkin the retainer biased into the collar locks the collar in the lockedposition. The first locking system is unlocked when an ampule having akey tab is inserted into the device with the key tab extending into aslot in the collar and in alignment with the link. A second lockingsystem including a groove on the slide and a detent collar followerlocks the slide into a first slide or slide locked position. The secondlocking system can be unlocked for actuation of the device only with thedetent collar in the second or unlocked position. The device may then beactuated with the user pushing the slide forward and then depressing thetrigger.

In a method of intermuscular and subcutaneous injection, an ampule issecured on an ampule receptacle thereby unlocking an ampule detectinginterlock. A trigger interlock is disabled or unlocked and a valve isactuated to release compressed gas to drive an injectant out of theampule.

These and other related objects are further achieved according to theinvention by an injection device having a housing, a pilot valveconnectable to a compressed gas source, a main valve operativelyconnected to the pilot valve, and a detent assembly for locking andunlocking a trigger which opens the pilot valve. Preferably, the detentswitch assembly includes a slide block having a slide block pin whichcan engage the trigger.

The ampule preferably comprises a generally cylindrical body havingampule walls which form an injectant chamber. A throat extends andtapers from the injectant chamber to a nozzle at one end of the ampule.Cam flanges are provided at the other end of the ampule for securing theampule to the injection device. Key tabs on the ampule adjacent andperpendicular to the flanges is provided for disengaging the firstlocking system of the injection device.

The ampule most desirably also has a generally cylindrical injectantchamber and a transition zone having a concave section adjoining theinjectant chamber. A convex section adjoins the concave section and aconical section adjoins the convex section. A nozzle at the front end ofthe ampule adjoins the conical section to reduce pressure losses andlower turbulence.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and features of the present invention will become apparentfrom the following detailed description taken in connection with theaccompanying drawings. It is to be understood, however, that thedrawings are designed for the purpose of illustration only and are notintended as a definition of the limits of the invention.

In the drawings wherein similar reference characters denote similarelements throughout the several views:

FIG. 1 is a perspective view of the present needleless injection devicein the ready for injection state;

FIG. 2 is a side view in part section of the injection device of FIG. 1;

FIG. 3 is an enlarged fragment view in part section of the valvemechanisms and gas delivery system of the device of FIG. 2;

FIG. 4 is an enlarged section view taken along line 4--4 of FIG. 3;

FIG. 5 is a top interior view taken along line 5--5 of FIG. 4;

FIG. 6 is a side view of the Luer fitting provided on the ampule shownin FIGS. 2 and 7; and

FIG. 7 is an enlarged section view fragment of an ampule which may beused with the injection device.

FIG. 8 is a perspective view of a second embodiment of the presentneedleless injection device in the ready for injection state;

FIG. 9 is an enlarged side view in part section of the injection deviceof FIG. 8;

FIG. 10 is a front elevation view taken along line 10--10 of FIG. 9;

FIG. 11a is an enlarged fragment view in part section of certainfeatures of the device of FIG. 8;

FIG. 11b is an enlarged fragment view in part section of certainfeatures of the device of FIG. 8 while the device is injecting;

FIG. 12 is an enlarged fragment in part section of the device of FIG. 8with a first locking system of the device unlocked by an ampule securedto the device;

FIG. 13 is an enlarged section view taken along line 13--13 of FIG. 9;

FIG. 14a is an enlarged fragment view in part section showing the frontend of the device of FIG. 8 before an ampule is secured into the device.

FIG. 14b is an enlarged fragment view in part section of the front endof the device of FIG. 8, as taken along line 14b--14b of FIG. 13 andshowing an ampule installed but not secured into the device;

FIG. 14c is an enlarged fragment view in part section of the front endof the device of FIG. 8, with an ampule installed and secured into thedevice;

FIG. 15 is an enlarged section view taken along line 15--15 of FIG. 14c;

FIG. 16 is an exploded perspective view of an ampule, a retainer and adetent collar of the device of FIG. 8;

FIG. 17a is a front elevation view in part section showing the ampuleinserted into the retainer of FIG. 16 but not secured therein;

FIG. 17b is a front elevation view in part section showing the ampulerotated and secured into the retainer of FIG. 16;

FIG. 18 is a front elevation view of the ampule of FIG. 16;

FIG. 19 is a rear elevation view of the ampule of FIG. 16;

FIG. 20 is a section view of the ampule taken along line 20--20 of FIG.19;

FIG. 21 is a front elevation view of an adapter plate to facilitate useof existing ampules with the device of FIG. 8;

FIG. 22 is a bottom elevation view of the adapter plate of FIG. 21;

FIG. 23 is a side elevation view of the adapter plate of FIG. 21 on anexisting ampule;

FIG. 24 is an enlarged front elevation view in part section of thecollar of FIG. 16;

FIG. 25 is a section view of the collar taken along line 25--25 of FIG.24;

FIG. 26 is a section view of the a third embodiment of the presentneedleless injection device in the ready for injection condition;

FIG. 27 is an enlarged section view of an ampule for use with theinjection device of FIG. 26;

FIG. 28 is an enlarged section view fragment of the nozzle of the ampuleof FIG. 27;

FIGS. 29(a) and 29(b) are enlarged views of the nozzle end of the ampuleof FIG. 27;

FIG. 30 is a section view of a third preferred ampule embodiment;

FIG. 31 is a side elevation view thereof;

FIG. 32 is an enlarged view fragment of the nozzle of the ampule of FIG.30;

FIG. 33 is a section view of a fourth preferred ampule embodiment;

FIG. 34 is a side elevation view thereof;

FIG. 35 is a section view fragment of tooling for molding ampulenozzles; and

FIG. 36 is an enlarged view fragment of the nozzle end of the ampule ofFIG. 27.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now in detail to the drawings, therein illustrated is a novelneedleless hypodermic injection device, which as shown in FIGS. 1 and 2includes a housing 22 and a cartridge holder 24 threaded onto aninternal threaded section 32 of the housing 22 and holding a cartridge28. At room temperature, the cartridge 28 contains a saturatedgas/liquid, such as CO₂ or some other appropriate pressure medium,hereinafter referred to as "compressed gas". An opening 26 is providedin the cartridge holder 24. A spanner collar 30 is threaded onto theinternal threaded section 32 of the housing 22 ahead of the cartridgeholder 24 and serves to hold other internal components in place.

Turning to FIG. 3, a piercing body 34 is contained within the housing 22against the spanner collar 30. An elastomeric washer 36 within thepiercing body seals against the facing end of the cartridge 28. Aslotted piercing pin 38 extends outwardly from the piercing body 34 intothe cartridge 28. The piercing pin 38 connects to a gas delivery tube46. A filter 40 and an orifice 42 are secured within the gas deliverytube 46.

Spaced apart from the piercing body 34 within the housing 22 is a valvebody 60. The valve body 60, housing 22, and piercing body 34 form areservoir 48 around the gas delivery tube 46. A bleed hole 44 leads fromthe gas delivery tube to the reservoir 48. A spacer 50 is optionallysecured around the gas delivery tube 46 within the reservoir 48 by a pin52.

An O-ring 54 seals the piercing body against the inner surface of thehousing 22. Similarly, an O-ring 56 seals the gas delivery tube 46 tothe piercing body 34.

At the other end of the gas delivery tube 46, an O-ring 62 seals the gasdelivery tube 46 to the valve body 60, with the gas delivery tubeextending into a bore 66 running through the valve body 60. A pilotvalve 72, preferably a Schrader-type valve, is contained within a pilotvalve chamber 74 within the valve body 60. The valve body 60 includes asleeve section 68 substantially containing a main valve piston 82. AnO-ring 80 seals the main valve piston 82 against the inner surfaces ofthe sleeve section 68 of the valve body 60 with the main valve piston 82slidably disposed therein. In between the main valve piston 82 and thepilot valve chamber 74 is a main piston chamber 76, with the bore 66also extending from the pilot valve chamber 74 to the main pistonchamber 76. As shown in FIG. 4, gas passageways 120 extend along theperiphery of the valve body 60 to connect the reservoir 48 to an annularchamber 84. The gas passageways 120 are designed to maximizeunrestricted flow from the reservoir 48 into the plunger chamber 114.

The main valve piston 82 includes a piston face 88 for sealing against avalve or liner seat 94 of a liner 92. Alternatively, the seat may beformed on an inwardly extending annular rim section of the housing 22.The main valve piston 82 and liner seat 94 form the main valve of theinjection device. The main valve piston 82 is advantageously made ofTEFLON and also preferably has a counter bore 86 for improved sealingcharacteristics.

A button 70 is held against the pilot valve 72 within a button housing98. An O-ring 64 seals the valve body 60 to the inner surface of thehousing 22, around the pilot valve 72 which passes partially through thehousing 22. A vent 78 extends through the button housing 98 into thepilot valve chamber 74.

The liner 92 has an opening 104 adjacent the liner seat 94 and is sealedagainst the inner surface of the housing 22 by O-ring 102. The sleevesection 68, the liner 92 and the main valve piston 82 form a seatchamber or annular chamber 84 on the side of the main valve piston 82opposite of the main piston chamber 76.

Within the liner 92 is a plunger driver 90 engaging a plunger 96. Aplunger driver orifice 112 extends through the plunger driver 90connecting the liner opening 104 to the plunger chamber 114. As shown inFIG. 2, a compression spring 116 is positioned on a hub 118 extendinginto the plunger chamber 114. The spring 116 biases the plunger driver90 against the end of the liner 92 adjacent the liner seat 94. An O-ring106 seals the plunger driver 90 against the liner 92.

Referring now to FIG. 7, a threaded collar 102 having a vent 122 leadingto the plunger chamber 114 joins the housing 22 and a threaded end 128of an ampule holder 130. Within the ampule holder 130 is an ampule 132having a base 146 abutting the threaded collar 102. The conicallytapered inner surface of the ampule holder 144 matches the conicallytapered outer surface 142 of the ampule 132, to support the ampule walls152 all around. With shallow angles of taper, there is a tendency forthe ampule 132 to stick in the ampule holder 130 after the injection.This is called a locking taper. The ampule 132 and ampule holder 130preferably have approximately a 16 degree taper which is advantageouslyabove the locking taper range. The ampule 132 is advantageously a singlemolded piece. A breech lock fitting may alternately be provided forquick ampule replacement.

The plunger 96 has a tapered end 124 and a seal 126 extending into aninjectant chamber 134 within the ampule 130. The plunger seal 126 sealsthe plunger 124 against the injectant chamber walls 136, which aresubstantially parallel. The injectant chamber 134 leads to a flow pathcomprising a first transition 138 extending into a throat 140 leading toa second transition 149 and a nozzle 148. The flow path smoothly makesthe cross section area reduction from the injectant chamber 134 to thenozzle 148, to minimize flow losses. Around the outside of the nozzleend of the throat 140 of the ampule 132 is an ANSI standard Luer fitting150 as detailed in FIG. 6. This fitting permits connection of the ampule132 to another medical device or container in a leak proof andmechanically secure manner. Advantageously, an ampule 132 made of orlined with glass or another material which does not interact with thedesired injectant may be used. The injectant chamber 134, firsttransition 138, throat 140, second transition 149 and nozzle 148 arepreferably molded in as part of the ampule during its manufacture.

A shield 160 is preferably provided over the ampule 132 and at leastpart of the ampule holder 130. The shield 160 includes a Luer sleeve 168adapted to fit over the Luer fitting 150 of the ampule 132. The frontsurface 162 of the shield 160 has ridges 164. A cylindrical flange 166extends back from the front surface 162 and engages the ampule holder130.

In operation, the cartridge holder 24 is unscrewed from the housing 22of the injection device 20. A compressed gas cartridge 28, such as a CO₂cartridge is placed into the cartridge holder 24. The cartridge holder24 is then threaded back onto the internal threaded section 32 of thehousing 22. As the cartridge holder 24 is turned to engage the housing22, the face end of the neck of the cartridge 24 engages, compresses andseals against the elastomeric washer 36 and the cartridge 28 is piercedby the piercing pin 38 projecting mom the piercing body 34. After thecartridge 28 is pierced, compressed gas flows by the piercing pin 38,through the filter 40 and the orifice 42. The filter 40 traps anycontaminants in the gas flow. The orifice 42 limits the flow rate.

Compressed gas flows through the orifice 42 and fills the duct 58 withinthe gas delivery tube 46. The gas continues to flow and fill the bore66, pilot eve chamber and the main piston chamber 76. Simultaneously,gas flows from the duct 58 through the bleed hole 44 in the gas deliverytube 46 to fill the reservoir 48. From the reservoir 48 the gas fluthrough the gas passageways 120 to fill the annular chamber 84. After asufficient interval, all chambers, spaces and flow channels are at apressure P1.

The spacer 50 is provided in the reservoir 48 to allow the volume of gascontained in the reservoir to be varied. This capability of varyingvolume enables the device to be used for subcutaneous (usuallyrelatively smaller volumes) and intramuscular (relatively largervolumes) injection. The bleed hole 44 is positioned adjacent to thevalve body 60 such that a wider spacer 50 may be provided withoutinterfering with the bleed hole 44. The diameter of the bleed hole 44 issmall in comparison to the flow areas of the duct 58, bore 66 and gaspassageways 120.

With device in the ready state, as described above and as illustrated inFIG. 3, the piston face 88 of the main valve piston 82 is sealed againstthe liner seat 94 of the liner 92, such that no gas may flow through theliner opening 104. The main valve piston 82 is forced against the linerseat 94 to make the seal by virtue of the pressure exerted on the backof the main valve piston, i.e., the surface facing the main pistonchamber 76. Although in the ready state, the annular chamber 84 and inthe main piston chamber 76 have equal gas pressure, the projected areaof the main valve piston 82 facing the main piston chamber 76 is greaterthan the projected area of the main valve piston 82 facing the annularchamber 84. The resulting force imbalance causes the main valve piston82 to be tightly sealed against the liner seat 94.

Using known techniques, the desired injectant is loaded into the ampule132. Single-use ampules may be provided as a unit along with the plunger96 and the shield 160. Unit-dose ampules prefilled with injectant mayalso be used. These ampules have a relatively larger surface around thenozzle 148 and no Luer fitting. Correspondingly, the throat 140 of suchampules may be shortened. The base 146 of prefilled ampules is sealedwith a plug or membrane.

With the ampule 132 loaded with injectant, the ampule holder 130 isplaced over the ampule 132 and the threaded end 128 of the ampule holder130 is engaged by the threaded collar 102. The plunger 96 passes throughthe threaded collar 102 and extends into the plunger driver 90 in theplunger chamber 114. (See FIG. 2.) The injection device is then readyfor injection, by placing the device 20 against the patient's skin. (SeeFIG. 1).

As the front surface or the ampule 132 is relatively small, the shield160 advantageously is provided over the Luer fitting 150 of the ampule132 to help steady the injection device 20 against the patient's skin.The ridges 164 on the front surface 162 of the shield 160 help toprevent sliding over the patient's skin and local anesthetic phenomenon.The flange 166 of the shield 160 covers the ampule holder surface 30 andis intended to help to prevent bodily fluids from contacting thereusable ampule holder 130.

During the injection sequence, substantial pressure is developed withinthe injectant chamber 134. Consequently, it is advantageous to avoidoverstressing the injectant chamber walls 136. The ampule holder 130 mayhelp to prevent excessively stressing the Luer fitting 150, thetransition 138 or the injectant chamber walls 136 of the ampule 132 byat least partially transferring stresses (which may be generated bylateral or bending movement of the nozzle 148 against the patient'sskin) to the ampule holder 130.

With the device 20 in the ready state and held against the patient'sskin, the device 20 is activated by depressing the button 70. Thiscauses the pilot valve 72 to open permitting the compressed gas in thepilot valve chamber 74 to escape through vent 78 to the outside.Simultaneously, the gas in the main piston chamber 76 rushes outwardlyalong the same path causing a substantial pressure drop therein. Thesmall diameter of the bleed hole 44 in the gas delivery tube 46 severelyrestricts the flow of gas from the annular chamber 84 through the gaspassageways 120 and reservoir 48 into the duct 58. Similarly, theorifice 42 severely restricts the flow of gas from the cartridge 28. Asa result, at the instant just after the button 70 is depressed, thepressure in the annular chamber 84 is far higher than the pressure inthe main piston chamber 76. The main valve piston 82 is thereby rapidlydriven in a snap action backwards towards the pilot valve chamber 74such that the seal between the piston face 88 and the liner 94 isopened, as shown in phantom in FIG. 3. The gas in the reservoir 48 isthen able to flow through the gas passageways 120 and through theopening 104 into the plunger chamber 114 to drive the plunger driver 90and plunger 96 into the injectant chamber 134 of the ampule 132. As theplunger 96 and plunger driver 90 move outwardly toward the ampule 130,the plunger chamber 114 is vented through the plunger chamber vent 122.The rapid acceleration of the plunger 96 causes the injectant to beinjected out of the nozzle 148 at a pressure and velocity sufficient topass through the patient's skin.

During the injection sequence, a small amount of compressed "bleed" gasmay also flow from the cartridge 28 and reservoir 48 into the pilotvalve chamber and out through the vent 78. However, this quantity of gasis acceptably small in comparison to the "driving" gas flowing from thereservoir 48 into the plunger chamber 114. In addition, since the volumeof the reservoir 48 is large compared to the initial "dead" volumebetween plunger driver 90 and the main valve, the rise in gas pressureacting on the plunger driver 90 is very fast.

Following the injection, the button 70 is released and the pilot valve72 closes. The gas pressures in the various ducts and chambers withinthe housing 22 then once again equalize and return substantially to P1.Specifically, compressed gas from the cartridge 28 flows through thebleed hole 44 to repressurize the reservoir 48 and through the duct 58to repressurize the bore 66 pilot valve chamber 74 and main pistonchamber 76. Due to the small size of the openings in the orifice 42 andthe bleed hole 44, this repressurization occurs slowly in comparison tothe injection sequence. As the main piston chamber 76 is repressurized,the main valve piston 82 is driven forward so that the piston face 88once again seals against the liner seat 94. In the plunger chamber 114,the spring 116 pushes the plunger driver 90 back against the opening104. As the plunger driver 90 is returned to its original readyposition, remaining gas in the plunger chamber 114 vents through theplunger driver orifice 112.

To prepare the device 20 for the next injection, the ampule holder 130,the ampule 132 and the plunger 96 are removed from the housing 22 byunscrewing the ampule holder 130 from the threaded collar 102. A newampule assembly 100 consisting of a new filled ampule 132, plunger 96,and shield 160 are installed on the device 20 as previously described.

Depending upon the particular application, the gas cartridge 28 issufficient for several injections. To replace the cartridge 28 after apredetermined number of injections, the cartridge holder 24 is unscrewedfrom the housing 22. As the cartridge holder 24 is being unscrewed fromthe housing 22, remaining compressed gas in the cartridge 28 may escapefrom the cartridge 28 into the interior of the cartridge holder 24. Theopening 26 at the end of the cartridge holder 24 prevents the cartridgeholder 24 from becoming pressurized, such that the cartridge holder 24may be easily removed from the housing 22. A new gas cartridge 28 isthen installed as previously described.

The device 20 may be used for intramuscular or subcutaneous injections.For subcutaneous injection, the nozzle 148 has a relatively smalleropening and the reservoir 48 is largely occupied by a spacer 50,limiting the gas volume therein to preferably as little as 20% of thefull reservoir volume. For intramuscular injection, a larger nozzle 148opening is advantageously used and the reservoir may be up to 100%filled with "driving" gas, i.e., no spacer is used. The nozzle 148opening may range in diameter and spacer 50 size (or length) determinewhether the device is set up for intramuscular or subcutaneousinjection.

Various other design alternatives will be apparent to those skilled inthe art. For example, the various O-rings which seal non-movingcomponents within the housing 22 may be replaced or eliminated by othertypes of seals (including adhesives) or internal construction. Inaddition, a diaphragm or bellows could be used in place of the mainvalve piston 82 and various other configurations of the valves, chambersand flow passageways are also possible.

FIGS. 8-25 illustrate a second embodiment of the injection device and anampule for use with this device. The second embodiment includes acompressed gas pressure indicator and interlock systems.

Referring to FIGS. 8, 9 and 10, the second embodiment of the device 200has a tubular housing 205 containing substantially the same elements asshown in FIG. 3. The structure and operation of these elements withinthe housing 205 are substantially the same as those described above andillustrated in FIG. 2-5. A gas cartridge holder 226 holding a cartridge28 is threaded on to the back or cartridge end of the housing 205. Athumb screw 228 is threaded through the cartridge holder 226 and extendsinto the cartridge chamber 225. A vent 229 extends through the cartridgeholder 226.

Referring specifically to FIG. 9, a slide assembly 201 having a slidetube 202 is fitted over the housing 205. A trigger 204 is pivotallymounted onto the housing 205 by a trigger pin 206 and protrudes throughthe top of the slide assembly 201.

Referring now to FIG. 11a, the slide assembly 201 has a ramp 209extending at an incline up to a trigger opening 220 in the slide tube202. A thumb rest 208 of the trigger 204 extends through the triggeropening 220. A planer trigger anvil 214 on the trigger 204 is positionedover a pilot valve pin 216 for actuating a pilot valve 218. The trigger204 has a trigger slot 210. A slide overhang 222 of the slide tube 202has a trigger stop 212 extending into the trigger slot 210. The triggerstop 212 prevents the trigger 204 from depressing the pilot valve pin216 to actuate the pilot valve 218, except when the device is unlockedduring an injection.

Forward of the trigger 204 is a compressed gas pressure indicatorassembly 230. The indicator assembly includes a Bourdon tube 238 havingan open end extending into an adaptor 242 threaded into an end cap 250which is sealed against a flattened portion of the housing 205 with anO-ring 246. The other side (top) of the end cap 250 is spaced apart fromthe slide tube 202 by a slide bushing 245. An O-ring 244 seals theadaptor 242 against the end cap 250. Similarly, an O-ring 224 seals thepilot valve 218 against the inside surface of the housing 205. A springcup 252 surrounding the adapter 242 supports the back end of acompression spring 240. The compression spring 240 extends forward overthe Bourdon tube 238 to a barrel 254 substantially surrounding anindicator cylinder 231. The indicator cylinder 231 is provided with aflag 236 having two different colored sections 235 and 237, for examplered and green. The two colored sections 235 and 237 are separated by ademarcation line 243.

A shaft 258 extends from the indicator cylinder 231 through a rotationbushing 256. An end support 234 mounted to the housing 205 supports therotation bushing 256. A window 232 made of a transparent material isprovided in the slide tube 202 over the indicator cylinder 231. Thewindow 232 is preferably provided with an axially extending referenceline.

Referring to FIGS. 9 and 11a, the open end 239 of the Bourdon tubeconnects to an opening 241 extending through the adaptor 242 and to aduct 248 passing through the bottom wall of the adaptor 242 and throughthe housing 205. As shown in FIG. 9, a duct extension 249 connecting tothe duct 248 passes through the valve body 60 to the pilot valve chamber219.

Referring to FIG. 11a, a bridge radius 260 extends from the slide tube202 overlying the indicator assembly 230 and is joined to a forwardextension 262 of the slide tube 202. As shown in FIGS. 9 and 11a, theforward extension 262 of the slide tube 202 has a lock groove 266forward of the connection to the bridge radius 260. An inwardlyextending rim 264 is provided at the other end of the forward extension262.

A retainer 282 within the slide tube 202 has three equally radiallyspaced apart hooks 292 (see FIG. 16). A threaded end of the retainer isscrewed onto a threaded end 272 of the housing 272, with the retainershoulder 289 clamping the end support 234 against the housing 205. Aplunger chamber end cap 274 is secured in between a retainer boss 275and the threaded end of the housing 272. A detent collar 340 is held inplace within the retainer 282 with a detent collar ring 341 slidablyheld against the retainer boss 275 by a wavy spring 278.

As illustrated in FIGS. 16, 24 and 25, the detent collar 340 has acylindrical collar surface 356 interrupted by three equally radiallyspaced apart crescents 352 extending forward from the detent collar ring341 to approximately the midpoint of the length of the detent collar340. In between the three crescent surfaces 354 are three equallyradially spaced apart slots 348 extending from the front surface 347 ofthe detent collar 340 rearward the detent collar ring 341. Chamferedguides 350 are provided at the front surface of the detent collar 347 oneither side of each slot 348. A collar plunger bore 358 extends axiallyand centrally through the detent collar 340. As shown in FIGS. 24 and25, adjacent to each slot guide 350 is a link or slide pin socket 344.The sockets 344 extend just slightly into the collar surface 356.Pressure relief bores 342 extend through the detent collar 340 from thefront surface 347 into the collar plunger bore 358.

The retainer 282, as shown in FIGS. 11a and 14a-3, has an ampule slot293 in between the retainer hooks 292 and the retainer body 295. (InFIGS. 14a-c, the bridge radius and housing are omitted for clarity.) Thedetent collar 340 is positioned inside of the retainer body 295. Asshown in FIG. 14a, slide pin holes 304 extend through the retainer body295. Slide pins 302 within the holes 304 are radially biased inwardlyonto the collar surface 356 of the detent collar 340 by a clock spring300 overlying the slide pines 302 in a clock spring groove 298. Theslide pins 302 are adapted to protrude into the link or slide pinsockets 344 on the detent collar 340, to reversibly lock the detentcollar from rotation within the retainer 282. Various alternativecollar-retainer link configurations to link or lock the detent collarfrom rotating in the retainer are feasible.

In the retainer body 295 behind the slide pin holes 304 is a detentcollar follower indicated generally as 283. In the preferred embodiment,the detent collar follower 283 includes inner and outer balls 284 and286 within three detent ball bores 296. The lower balls 284 rest on thecollar surface 356 such that the outside balls 286 protrude into thelock groove 26 of the forward extension 262 of the slide tube 202. Otherdetent collar follower configurations including pins and expandablerings are also possible.

In use, a compressed gas cartridge 28 is first installed into the device200. Specifically, the cartridge holder 226 is unscrewed from thehousing 205 and a cartridge 28 is inserted into the cartridge chamber 28with the thumbscrew 228 substantially backed out of the cartridgechamber 225. The cartridge holder 226 is then threaded back onto thehousing 205 with the neck of the cartridge 228 facing the piercing pin38 and the elastomeric washer 36 (see FIGS. 3 and 9). The thumbscrew 228is then turned inwardly or forward to force the compressed gas cartridge28 onto the piercing pin 38. Compressed gas then flows from thecompressed gas cartridge 28 into the device as described above for thedevice of FIGS. 1-3.

As shown in FIGS. 11a and 14a, no ampule 306 is yet installed in thedevice 200 and the device 200 is in a locked condition. The trigger 204cannot be depressed to actuate the pilot valve 218 because the triggerstop 212 holds the trigger anvil 214 away from the pilot valve pin 216.The trigger stop 212 cannot be pushed or slid forward out of the triggerslot 210 because the lock groove 266 on the forward extension 262 of theslide tube 202 interferes with and cannot pass over the outer ball 286of the collar follower 283. The outer balls 286 are held in the "up"position into the lock groove 266 by the lower balls 284 which in turnare resting on the collar surface 356 of the detent collar 340. Thedetent collar 340 is held in position relative to the retainer 282 slidepins 302 biased into the slide pin sockets 344 on the detent collar 340,by the clock spring 300. Consequently, in this state, the crescents 352on the detent collar 340 cannot be moved into alignment with the innerballs 284. Thus, with no ampule secured into the device 200, the devicecannot be actuated and no compressed gas can be released.

Referring now to FIGS. 12, 13, 14b and 20, an ampule 306 containing aninjectant in the injectant chamber 388 is inserted into the front end ofthe device 200 by pushing in and turning within the retainer 282. Theradial or key tabs 312 on the back of the ampule 306 are aligned withthe slots 348 in the detent collar 340. The flanges 316 of the ampule306 pass in between the retainer hooks 292 as the ampule 306 isinserted.

As the radial tabs 312 slide into the slots 348, the slide pins 302 rideup on the outside surfaces of the radial tabs 312 causing the slide pins302 to lift out of the slide pin sockets 344. The detent collar 340 isthen free to rotate within the retainer 282. This condition is shown inFIGS. 13 and 14b wherein the slide pins 302 (shown in phantom) arepushed out of the slide pin sockets 344 by the radial tabs 312 againstthe force of the clock spring 300. Although this link or slide pinlocking system from locking the detent collar 280 to the retainer 282 isunlocked or disengaged, the device cannot be activated as the outerballs 286 still prevent forward movement of the slide tube 202 therebypreventing removal of the trigger stop 212 from the trigger slot 210.

The ampule 306 is then rotated along with the detent collar 340 withinthe retainer 282. The grip tab 308 on the ampule 306 provides a fingergrip for gripping the ampule. While the ampule is turned it is alsoslightly pressed towards the back of the device 200 thereby compressingthe wavy spring 278. The cams 310 on the cam arms 322 of the flange 316on the back of the ampule 306 slide and wedge under the retainer hooks292 (see FIG. 16).

The ampule 306 is turned until the stops 324 come to rest against thesides 297 of the retainer hooks 292, as shown in FIGS. 17a and 17b. Asthe detent collar 340 rotates with the ampule 306, the crescents 3564come into alignment with the detent ball bores 296, thereby allowing theinner balls 284 to come to rest on the crescent surfaces 354. Thisallows the outer balls 286 to drop from the lock groove 266 asillustrated in FIGS. 14c and 15.

The link interlock 301 (comprising the biased slide pins 302 and sockets344 for locking the detent collar 340 against rotation) and the collarfollower interlock 283 (comprising the crescents 354 and balls 284 and286 for preventing movement of the slide tube 202) have now both beenunlocked or disabled. However, the slide tube 202 remains biased to theback of the device 200 by the compression spring 240. Consequently, thetrigger stop 21 remains in the trigger slot 210 to prevent depression ofthe trigger 208.

To administer an injection, the device 200 is positioned with the nozzleand shroud 334 of the ampule 330 against the injection site on thepatient. The user then slides the slide tube 202 forward with thumb orhand pressure on the ramp 209, overcoming the biasing force of thespring 240. This movement of the slide tube 202 and trigger 208 may beperformed with one or two hands. As the slide tube 202 moves forward,thetrigger stop 212 moves out of the trigger slot 210 allowing the trigger208 to be fully depressed to actuate the injection sequence.

FIG. 11b illustrates the condition of the device 200 while injecting.The trigger stop 212 is temporarily displaced forward allowing thetrigger 208 to pivot downwardly with the trigger anvil 214 depressingthe pilot valve pin 216 to open the pilot valve 218. The elements withinthe housing 205 then operate as described above for the embodiment ofFIGS. 1-3. The pressure relief bores 342 extending through the collar340 and linking with the channels 336 in the ampule 306 provide a routeto the outside of the device for relief of compressed gas exhaustingfrom the plunger chamber 114 during actuation.

After the injection, the trigger 208 is released and biased to pivotaway from the pilot valve pin 216. When the slide tube 202 is releasedby the user,the trigger stop 212 returns into the trigger slot 210.(FIG. 11a). The lock groove 266 moves back over the detent ball bores296. The ampule 306 is rotated in the reverse direction along with thedetent collar 340 and the ampule is removed from the device 200, therebyresetting or relocking the link and collar follower locking systems. Theelements within the housing 205 correspondingly return to their originalpositions as described above with reference to FIGS. 1-3.

The indicator assembly 230 indicates whether the pressure of thecompressed gas within the device 200 is sufficient for anotherinjection. The Bourdon tube 239 is calibrated in a known manner torotate with changes of pressure within the Bourdon tube 239. As shown inFIG. 9, the duct 248 and duct extension 249 connect the Bourdon tube 239with the pilot valve chamber 219, such that the pressure in the Bourdontube equals the pressure in the pilot valve chamber. As the pressure ofthe compressed gas in the device 200 decreases with each injection, thepressure within the Bourdon tube correspondingly decreases this causesthe Bourdon tube 239 to turn the indicator cylinder. By looking throughthe window 232, the user the can view the flag 236 to determine if thereis sufficient gas pressure for another injection. The bourdon tube 238and indicator cylinder 231 are arranged so that when the gas pressurewithin the device 200 is sufficiently high, the green side 237 of theflag 236 appears in the window 232. As the gas pressure decreases, theindicator cylinder 231 turns with the red side 235 of the flag 236gradually appearing in the window 230. When the red side 235 occupies apredetermined position in the window 232, the device no longer hassufficient pressure of another injection ad the cartridge 28 must bereplaced.

The adapter plate of FIGS. 21-23 is used to operate the device withother ampules to having the key tabs 312.

FIGS. 26 illustrates a third embodiment of the present needlelessinjection device. As illustrated therein, an ampule 406 is secured to aretainer barrel 408 of a housing tube 412 of the injection device 400.Retainer hooks 410 to the retainer barrel 408 engage the flanges 316 ofthe ampule 406. A pressures plate 414 is biased by a wavy spring 416against the back of the ampule 406 to secure it in place within theretainer barrel 408.

A plunger driver 418, similar to plunger driver 90, has a spring bore420 and an eccentric vent 422 leading to an orifice insert 424 leadingto the liner opening 104. The offset position of the eccentric vent 422helps insure free return of the plunger driver 418 after injection.

Adjacent to the valve body 60, the spacer 50 leaves a very small volumereservoir 211, as the remaining compressed gas filling the spaces in thevarious chambers and passageways (which are the same as in the previousembodiment) provide adequate volume of compressed gas for injection.

An upper housing 426 is fixed in position on the outside of the housingtube 412, e.g., with screw fasteners and/or adhesives. An anchor bushing4528 is attached to the outside of the housing tube 412 and is furthersecured in place by the upper housing 426. The anchor bushing 428supports the rotation bushing 256. An enlarging window 430 is providedont he upper housing 426 to permit viewing of the compressed gaspressure indicator assembly 230.

A trigger lever 440 is pivotally mounted to the housing tube 412 by apivot pin 442. The trigger lever 440 has a locking slot 446 and anextension 447 extending through a cut out 458 in the upper housing 426.A leaf spring 444 biases the trigger lever 440 away from the housingtube 412. A boss 445 on the trigger lever 440 rests on top of the pilotvalve stem 216. A slide block 448 is slidably mounted onto the housingtube 416. A slide block pin 450 extends from the slide block 448 and isengageable into the locking slot 446 of the trigger lever 440.

A detent switch assembly 452 is provided on the slide block 448. Thedetent switch assembly includes a detent button 453 extending throughthe cut out 458, a spring 444 and a detent plate 456 having protrusions455 and 457 which are held against a detent surface 459.

Referring to FIG. 27, the ampule 406 is similar to ampule 306 (FIG. 9)but has a generally flat rear surface 461 without tabs 312. These tabsare not required as the injection device of FIG. 26 does not have theampule interlock system shown in the device of FIG. 9.

Referring once again to FIG. 27, the ampule, which is preferablyinjection molded as a single part of a polycarbonate such as clear LEXANHP2, has an injectant chamber 338, a transition zone 460 and a nozzle470. A first or concave radius 464 begins at a tangent point 462. Asecond or convex radius 466 adjoins the first radius 464. A conicaltaper 468 extends from the nozzle 470 to the second radius 466. Thisprovides a smooth transition zone 460 between injectant chamber andnozzle to avoid stress concentrations in the ampule 406 and provide goodinjection characteristics. FIG. 36 shows preferred dimensions of thenozzle end of ampule 406, with R1 and R2 at 0.19 in., dimension E at0.432 in. angle alpha at 14 degrees and an injectant chamber insidediameter of 0.250 in. nominal.

As shown in FIG. 28, the nozzle 470 extends a short distance beforejoining the conical taper 468. The nozzle diameter can vary, dependingon application, e.g., intramuscular, subcutaneous, veterinarian, etc.FIG. 18 substantially illustrates the mounting tabs 316 of the ampule406.

As shown in FIGS. 29a and 29b, the front portion of the shroud 334 ofthe nozzle 406 includes serrations 472 (instead of the finger block 308,as shown in FIG. 16) to provide a gripping surface.

In use, the ampule 406 is filled with injectant and is placed into theinjection device 400 by passing the flanges 316 of the ampule 406 by theretainer hooks 410 on the retainer barrel 408. The pressure plate 414 isdepressed slightly against the wavy spring 416. The ampule 406 is thenrotated such that the flanges 316 engage the retainer hooks 410. Thepressure plate 414 then clamps the ampule 410 in place within theretainer barrel 408.

The nozzle 470 of the ampule 406 is placed onto the injection site. Theuser pushes the detent button 453 forward, to switch the detent switchassembly from a locked to an unlocked position. As the detent button 453is pushed forward, the slide block 448 slides forward and the slideblock pin 450 disengages from the locking slot 446 on the trigger lever440. The device 400 is then ready to inject. The trigger lever 440 isdepressed to commence the injection sequence as previously described inthe other embodiments. As the plunger 418 moves forward during theinjection sequence, ambient gas in the plunger driver chamber isexpelled by passing through relief holes 415 in the pressure plate 414,in between the flanges 316 of the ampule 406 and out of the front of thedevice 400.

After the injection, the spring 444 pushes the trigger lever 440 up,once it is released. The detent button 453 is returned to the lockedposition and the slide block pin 450 once again engages the locking slot456 to prevent actuation of the device 400.

Generally, with hand power syringe/needles, the interior pressures arelimited to a few psi, rarely or never exceeding about 30 psi. Thislimits the pressure producing forces on the ampule. Thus, the syringecan be thin-walled since stresses produced by the compressed injectantare low. On the other hand, with the compressed gas powered injectiondevices described herein, the pressures generated within the ampules maybe orders of magnitude greater, i.e., in the range of approximately3,000-6,000 psi. These higher pressures are necessary to generate aliquid jet with sufficient velocity to pierce the skin without a needle.

To achieve such a jet velocity that will pierce the skin at minimum painlevels, two basic jet characteristics should be provided:

1. The velocity profile across the jet diameter should be as flat aspossible (not parabolic as in highly viscous tubular flow). This ensuresthat momentum of the jet will be sufficient, not only to initiallypierce the skin, but also to momentum control depth of penetration.

2. Turbulence in the jet should be minimized to enhance axial momentumand additionally to minimize jet spreading due to turbulent transversevelocity components.

These characteristics can be achieved with proper nozzle design, inparticular, the converging section between the larger cylindrical boreand the final cylindrical nozzle section. The converging transitionshould be without any rapid or step changes in cross-section. Longlinearly tapered nozzles can provide characteristics 1 and 2 above.However, such designs have larger pressure losses, and are lesspractical for a disposable device since they use relatively largevolumes of material. At the other extreme, a sharp edged hole in aperpendicular cylinder end can work as a nozzle but the resulting jetwill generally not have characteristics 1 or 2 above. The preferredcompromise, considering pressure losses versus characteristics 1 and 2above and material requirements, is to have a short nozzle usingconnecting radii. This preferred design yields the least turbulence forgiven length.

To operate with the relatively higher injection pressures, the plunger96 has a back-up ring 127 behind the O-ring 126, as shown in FIG. 7. Inaddition, the diameter of plunger 96 diameter is maximized to loweraxial compressive stresses and for maximum resistance to column bucklingwithin the space allowed.

The ampules shown in FIGS. 7, 20, 27 and 30-33 are designed to withstandthe relatively higher injectant pressures generated during the injectionsequence. One critical area in the ampule design is the Luer tip end.FIG. 32 depicts the nozzle and throat of the ampule shown in FIG. 27, aswell as the ampule 500 shown in FIG. 30 and the ampule 600 shown in FIG.33. Referring to FIG. 32, with a short nozzle length, the fluid coneangle alpha would conventionally be large, in the range of, for example,20-30 degrees. In contrast, the standard Luer tip dimensions require acertain minimal axial length. The critical stress intensity occurs atthe minimum section thickness, where the Luer taper transitions to theradius extending to the injectant chamber diameter. Thus, the fluid coneangle alpha must be reduced to keep stresses within safe limits.Resulting fluid cone angles (alpha) of 4-12 degrees are accordinglypreferred, although these angles incur a small additional pressure drop.

Another stress concentration area of the ampules is at the rear or lugend. As shown in FIGS. 9 and 26, the ampules 306 and 406 (as well as theampules of FIGS. 30-34) have three lugs which are attached to theinjection device at the outer edge of the lugs. During injection, thereis about a 200-pound axial load divided among the three lugs, inaddition to the internal radial pressure loading on the ampule. Thisaxial load causes high stress intensities at the corners where the lugsattach to the cylindrical ampule body. Accordingly, the lugs preferablyhave a gradual change in cross-section and a relatively large radius(for example, 0.093 in.) joining the lugs to the ampule body, as shownat R3 in FIG. 30.

Since the ampules are preferably disposable, their cost is minimized byreducing the material required for each ampule. Sufficient material mustnevertheless be provided to maintain stresses at acceptable levels.Ampule 500 shown in FIG. 30 illustrates an ampule similar to ampule 27but manufactured using less material.

Referring still to FIG. 30, the preferred contour design of thetransition from the injectant chamber 502 of the ampule 500 to thenozzle 504 is defined by the concave radius R1 and convex radius R2,preferably both 0.19 inch. The nozzle end 506 of the ampule 500protrudes by dimension F, preferably 0.020 inch beyond the ends of theshroud 508. This protrusion facilitates secure engagement of the nozzleagainst the patient's skin. The shroud length indicated by dimension Gis preferably 0.310 inch and the dimension E from the tangent point tothe nozzle is preferably 0.501 inch. The base or lug end diameter A ispreferably 0.420 in. The wall thickness most desirably ranges from 0.084near position B where the ampule outside diameter is 415 in., to 0.075at position C where the ampule outside diameter is 0.402 in. With atotal overall ampule length of 1.720 in., the spacing between positionsB and C is preferably 0.823 in., with position B 0.370 in. from the lugend of the ampule. The injectant chamber diameter 502 nominally has apreferred diameter of 0.250 in. The ampule is designed for manufactureby injection molding and has appropriate draft angles. The nozzle end ofampule 500 is configured to the standard male Luer fitting. The anglealpha is preferably 10 degrees. As shown in FIG. 31, the ampule 500 hasa series of radially extending ridges 510 to facilitate gripping theampule by hand.

Ampule 500 carries 0.5 ml volume of injectant. Ampule 600 shown in FIG.33 is similar to the ampule 500 but is formed with an injectant chamber602 having a larger nominal injectant chamber diameter (0.304 in.) andholding 1.0 ml of injectant. Radii R6 and R7 are 0.22 in., alpha is 10degrees, L is 0.021, the tangent point is 1.219 from the lug end, andthe overal length is 1.647. The features shown on ampules 132 (FIG. 7)and 306 (FIG. 16), for example, the shield 160 or channels 336 forexhausting compressed gas may also be used with ampules 406 (FIG. 27),500 (FIG. 30) or 600 (FIG. 33).

The nozzle section L/D ratio is another factor that helps maintainminimum jet spreading and transverse turbulent momentum. Ratios from 2to 5 provide a good compromise to damp transverse velocity withoutincurring too high a nozzle pressure drop. An L/D ratio of 2.5 is mostpreferred. The nozzle diameter D ranges from approximately 0.0040 to0.0250 in. With an L/D ratio of 2.5, L ranges from 0.0100 to 0.0625. Theradius R5 in FIG. 32 is preferably 10×D.

P4 is preferably a sharp corner. A substantial radius at P4 will createa bell mouth design allowing the jet of injectant to possibly diverge asit exits the ampule during injection.

FIG. 35 shows manufacturing tooling for injection molding ampules, suchas ampule 500. A core pin 700 has a fine wire tip 702 ground onto itsleading end. The wire tip 702 extends into a matching hole in a pilotguide 704. The wire tip 702 allows for the injection molding of verysmall diameter orifice openings, facilitates sharp corners at P4 (FIG.32), centers the nozzle opening and provides added rigidity to resisttransverse flow of plastic during injection molding.

Thus, while several embodiments of the present invention have been shownand described, it will be obvious that many changes and modificationsmay be made thereunto, without departing from the spirit and scope ofthe invention.

We claim:
 1. In an ampule of the type used with an injector to provide aneedleless injection, and having an ampule body forming an injectantchamber and a nozzle section adjoining the ampule body and forming anozzle opening, the improvement comprising:a tubular shroud attached tothe ampule body and concentric with the nozzle section; and a Luerfitting on the nozzle section and substantially within the shroud, theLuer fitting having a minimum diameter of approximately 0.15 inchadjacent to the nozzle opening and tapering linearly outwardly to largerdiameters towards the injectant chamber.
 2. The ampule of claim 1wherein the injectant chamber is cylindrical and concentric with thenozzle opening.
 3. The ampule of claim 1 further comprising means forattaching the ampule to an injection device.
 4. The ampule of claim 3wherein the means for attaching comprises a plurality of lug sectionsradially projecting from the ampule body and spaced apart from thenozzle section.
 5. The ampule of claim 1 further comprising a plungerslidably positioned at least partially within the injectant chamber. 6.The ampule of claim 1 wherein the nozzle section projects beyond thetubular shroud.
 7. The ampule of claim 1 further comprising:a nozzlebore of length L in the nozzle section, a throat section between theampule body and the nozzle section, the throat section having innerthroat walls leading and tapering substantially conically outwardly fromthe nozzle bore towards the injectant chamber.
 8. The ampule of claim 7further comprising a transition section between, and adjoining, thethroat section and the ampule body, the transition section havingforward inner transition walls curving on a radius convexly from thethroat section into rear inner transition walls, the rear innertransition walls curving on a radius concavely from the forward innertransition walls to the ampule body.
 9. The ampule of claim 7 whereinthe throat section has inner walls which flair conically outwardly froma center line of the ampule at an angle in the range of approximately2°-6°.
 10. The ampule of claim 7 wherein throat section has a length aplurality of times greater than the length of the nozzle bore L.
 11. Inan ampule of the type used with an injector to provide a needlelessinjection, and having an ampule body forming an injectant chamber and anozzle section adjoining the ampule body and forming an nozzle opening,the improvement comprising:a nozzle section having a nozzle bore oflength L; a throat section adjoining the nozzle section and having innerthroat walls leading and tapering substantially conically outwardly fromthe nozzle bore, the throat section having a length a plurality of timesgreater than the length of the nozzle bore L; a cylindrical ampule bodyadjoining the throat section and containing an injectant chamber; atubular shroud attached to the ampule body and extending substantiallyover the entire throat section; and a Luer fitting on the nozzle sectionsubstantially within the shroud.
 12. The ampule of claim 11 wherein theshroud has a length of approximately 0.3 inches.
 13. The ampule of claim11 wherein the shroud has a forward end rim with an outside diameter ofapproximately 0.4 inch.
 14. The ampule of claim 11 further comprising aplurality of lug sections radially projecting from the ampule body. 15.The ampule of claim 11 wherein the nozzle section projects beyond thetubular shroud.
 16. The ampule of claim 11 further comprising atransition section between, and adjoining, the throat section and theampule body, the transition section having forward inner transitionwalls curving on a radius convexly from the throat section into rearinner transition walls, the rear inner transition walls curving on aradius concavely from the forward inner transition walls to the ampulebody.
 17. The ampule of claim 11 wherein the throat section has innerwalls which flair conically outwardly from a center line of the ampuleat an angle in the range of approximately 2°-6°.
 18. In an ampule of thetype used with an injector to provide a needleless injection, and havingan ampule body having a front and a back end and containing an injectantchamber and a nozzle section forming a nozzle and adjoining the ampulebody, the improvement comprising:a tubular shroud attached to the ampulebody, concentric with the nozzle section; a Luer fitting on the nozzlesection and substantially within the shroud; a conical throat sectionadjoining the ampule body and the nozzle section and forming a conicalthroat for connecting the injectant chamber to the nozzle; and aplurality of lugs at the back end of the ampule body radially spacedapart from each other.